As a wide-bandgap semiconductor material, diamond possesses excellent performances, such as high breakdown field, radiation resistance, high thermal conductivity, etc. Diamond substrate device has advantages of high working temperature, great breakdown field, high cutoff frequency, large power density, etc., and would be the first choice for high power microwave devices, power electronic devices, surface acoustic wave devices, and so on in the future. The diamond has a wide bandgap and a tight atomic structure, and currently cannot be performed with effective n-type doping. An existing method for fabricating an n-type conductive channel is element doping method, which generally uses element phosphorus to perform the n-type doping, however, activation efficiency of such doping method is very low, and when a concentration of the phosphorus doping is 5×1017 cm−3, the mobility is reduced to 410 cm2/V·s.
The highest electron mobility of the phosphorus doping at the room temperature disclosed by existing reports is 780 cm2/V·s (room temperature), which is far from reaching a theoretical value of the diamond or playing the intrinsic excellent properties of such material. A basic physical mechanism of such doping method is as follows: impurities are ionized to release excess carriers, while under a low doping concentration, ionization of impurities is strongly inhibited, the activation rate is extremely low, and under a high doping concentration, the introduction of the doping may result in relatively strong scattering of ionized impurities, which affects the mobility of the carriers and make the mobility of the carriers almost reduced to 0. These make the doping problem of the diamond material be a worldwide problem, which may greatly restrict the development of the diamond semiconductor, since an effective p-n junction cannot be formed unless the n-type doping problem is tackled. Thus, to realize the effective and stable n-channel is a primary step for promoting the application of the diamond semiconductor material.